One type of telecommunication service that a telecommunication service provider provides to a subscriber is DS-1 service (also referred to here as a “DS-1 line” or “T1 line”). One approach to providing DS-1 service to a subscriber is to provide DS-1 service over two twisted-pair telephone lines that run from a central office of the service provider directly to the subscriber's premise. This approach is not suitable, however for providing service to all subscribers.
Another approach to providing DS-1 service to subscribers (for example, subscribers located relatively far from the central office of the service provider) is to deploy a remote enclosure (also referred to as a “remote terminal” or “remote hut”) in the outside plant. The outside plant is the portion of the service provider's network that is located outside of the central office. Multiple DS-1 lines are multiplexed together and communicated between the central office and the remote enclosure over a higher-speed communication channel (for example, a DS-3 channel or OC-3 channel). An appropriate communication medium or media is provided between the central office and the remote enclosure (for example, multiple twisted-pair telephone lines or one or more optical fibers). The higher-speed communication channel is carried over the communication medium.
In one configuration, multiple equipment shelves are housed within the remote enclosure, with each equipment shelf handling a subset of the DS-1 lines provided over the high-speed communications channel (for example, using appropriate DS-1 line interface units). In one such configuration, the shelves are arranged so that one shelf (referred to here as the “master” shelf) interfaces directly to the higher-speed communication channel (for example, via an appropriate multiplexer unit). The other shelves (referred to here as “subtended” shelves) are subtended from the master shelf. The master shelf splits the high-speed channel into the various subsets of DS-1 lines and routes one subset to the DS-1 line interface units housed within the master shelf. The other subsets are routed to respective subtended shelves for processing therein.
Service providers typically wish to manage such a remote enclosure remotely (that is, without requiring a technician to travel to the remote enclosure to configure and monitor the remote enclosure). One general approach to doing this involves embedding management and/or control messages (for example, TL-1 messages) into a higher-speed communication channel provided between the central office and the remote enclosure. However, where an OC-3 channel is provided between a central office and a remote enclosure that houses multiple equipment shelves arranged with one or more equipment shelves subtended from a master shelf, any management commands embedded in the OC-3 channel are typically terminated at the OC-3 multiplexer unit of the master equipment shelve. Consequently, management commands are typically not addressed to the DS-1 line interface units in the master equipment shelf nor to any units housed in the subtended equipment shelves. In such a configuration, the DS-1 line interfaces in the master equipment shelf and all the units in the subtended equipment shelves are typically not able to be remotely managed using such embedded management commands.